Rough calcs won't cut it. Keep in mind, most people are stuck in a position and do not want to move. Heck, some MMM forum members espouse suffering now to play later. I get it, and have done it most of my adult life.
This is related to your situation because there is a big unknown when it comes to buying a business, or starting a business. When I started my small business 18 months ago, all I heard from family and friends is no, no, no. I started cash-flowing day one and it has accelerated my FIRE plans tremendously.
Don't look without for yeas or nays, look within. But most importantly, make sure your #s are right, and make you understand that the buck stops with you. I spend less than 2 hours/week on my small business, but it makes me more than your salary currently. HOWEVER, when I started the small business, I was quite easily working 120 hours/week between my day job and setting up the small business. That's 18 hours/day, 7 days/week, for months, with a new baby at home waiting for me at the end of the work day.
Best of luck on your future endeavors.